Drosophila melanogaster and Drosophila hydei are flightless.....as long as you don't put them together, then they aren't flightless anymore.

The way I dust them is by using a paper cup. I pour a little powder in, then I rub some powder around the sides of the cup (they can climb the cup but when the reach the powder they will fall off). Then I pour some flies in and swish them around.